r9 280x 15.3mh/s whit 12.3 drivers
r9 280x 12.5mh/s whit 14.6 drivers
windows 8.1

setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_USE_SYNC_OBJECTS 1
sgminer.exe -k groestlcoin -o stratum+tcp://cryptohunger.com:3333 -u guidosuller -p xxx -d 0,1,2,3,4 -I 22 -g 1 --thread-concurrency 11200 --gpu-engine 1150 --gpu-memclock 750 --lookup-gap 0 -w 256 --auto-fan --gpu-fan 30-85,30-85,30-85,30-85,30-85 --temp-cutoff 95,95,95,95,95 --temp-overheat 85,85,85,85,85 --temp-target 72,72,72,72,72